jails.http.converter.ResourceHttpMessageConverter.java Source code

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Here is the source code for jails.http.converter.ResourceHttpMessageConverter.java

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/*
 * Copyright 2002-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jails.http.converter;

import jails.http.HttpHeaders;
import jails.http.HttpInputMessage;
import jails.http.HttpOutputMessage;
import jails.http.MediaType;

import java.io.IOException;
import java.io.InputStream;
import java.util.Collections;
import java.util.List;
import javax.activation.FileTypeMap;
import javax.activation.MimetypesFileTypeMap;

import org.springframework.core.io.ByteArrayResource;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.util.ClassUtils;
import org.springframework.util.FileCopyUtils;
import org.springframework.util.StringUtils;

/**
 * Implementation of {@link HttpMessageConverter} that can read and write {@link Resource Resources}.
 *
 * <p>By default, this converter can read all media types. The Java Activation Framework (JAF) - if available - is used
 * to determine the {@code Content-Type} of written resources. If JAF is not available, {@code application/octet-stream}
 * is used.
 *
 * @author Arjen Poutsma
 * @since 3.0.2
 */
public class ResourceHttpMessageConverter implements HttpMessageConverter<Resource> {

    private static final boolean jafPresent = ClassUtils.isPresent("javax.activation.FileTypeMap",
            ResourceHttpMessageConverter.class.getClassLoader());

    public boolean canRead(Class<?> clazz, MediaType mediaType) {
        return Resource.class.isAssignableFrom(clazz);
    }

    public boolean canWrite(Class<?> clazz, MediaType mediaType) {
        return Resource.class.isAssignableFrom(clazz);
    }

    public List<MediaType> getSupportedMediaTypes() {
        return Collections.singletonList(MediaType.ALL);
    }

    public Resource read(Class<? extends Resource> clazz, HttpInputMessage inputMessage)
            throws IOException, HttpMessageNotReadableException {

        byte[] body = FileCopyUtils.copyToByteArray(inputMessage.getBody());
        return new ByteArrayResource(body);
    }

    public void write(Resource resource, MediaType contentType, HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException {

        HttpHeaders headers = outputMessage.getHeaders();
        if (contentType == null || contentType.isWildcardType() || contentType.isWildcardSubtype()) {
            contentType = getContentType(resource);
        }
        if (contentType != null) {
            headers.setContentType(contentType);
        }
        Long contentLength = getContentLength(resource, contentType);
        if (contentLength != null) {
            headers.setContentLength(contentLength);
        }
        FileCopyUtils.copy(resource.getInputStream(), outputMessage.getBody());
        outputMessage.getBody().flush();
    }

    private MediaType getContentType(Resource resource) {
        if (jafPresent) {
            return ActivationMediaTypeFactory.getMediaType(resource);
        } else {
            return MediaType.APPLICATION_OCTET_STREAM;
        }
    }

    protected Long getContentLength(Resource resource, MediaType contentType) throws IOException {
        return resource.contentLength();
    }

    /**
     * Inner class to avoid hard-coded JAF dependency.
     */
    private static class ActivationMediaTypeFactory {

        private static final FileTypeMap fileTypeMap;

        static {
            fileTypeMap = loadFileTypeMapFromContextSupportModule();
        }

        private static FileTypeMap loadFileTypeMapFromContextSupportModule() {
            // see if we can find the extended mime.types from the context-support module
            Resource mappingLocation = new ClassPathResource("org/springframework/mail/javamail/mime.types");
            if (mappingLocation.exists()) {
                InputStream inputStream = null;
                try {
                    inputStream = mappingLocation.getInputStream();
                    return new MimetypesFileTypeMap(inputStream);
                } catch (IOException ex) {
                    // ignore
                } finally {
                    if (inputStream != null) {
                        try {
                            inputStream.close();
                        } catch (IOException ex) {
                            // ignore
                        }
                    }
                }
            }
            return FileTypeMap.getDefaultFileTypeMap();
        }

        public static MediaType getMediaType(Resource resource) {
            String mediaType = fileTypeMap.getContentType(resource.getFilename());
            return (StringUtils.hasText(mediaType) ? MediaType.parseMediaType(mediaType) : null);
        }
    }

}